Mirrored lens protractor



.April 7, 1925.

l.. w. BUGBEE, JR

MIRRO'RED LENS PROTRACTOR Filed June '7, 1924 CTL ,//y /l//l/ll/ ///////ll INVENTOR. l ac/fm' W 5061555, Je.

A TTORNEYS.

Cil

Patented Apr. 7, Y1925,.

UNITED STATES Lucian W. suenan, an., or mnrnnaronrs,

PATENT innerer...-

manana," nssreiroa *fro ionnrrnon MIRRORED LENS p'rnornncron.

Vuippiieafnm mediana 7', 1924. :serial sro. massa vide -a protractor for lens blanks and' finished lenses which Will avoid the-errors of protractors heretofore in use Whenever the inspection-fis notfabsolutely perpendicular or radial-totheprotractor, by insuring the inspector Vusing the same that `his in-` spection is exactly perpendicular or radial to the protractor andthe lens lor blank thereon. f `Such 'protractor is -used Afor laying out lens blanks andproperly marking the same preparatory to grinding, finishing or other'further treatmentand for inspecting finished lenses and their mounting.

This invention is also of particular value in connection with the inspection of bifoca-l lenses or lens blanks for centering and decentering the same and locating the meridians of the lenses or blanks for aiding in the scientific finishing of the prescription side of a onepiece bifocal lens, or for edging and otherwise forming` the lenses for their accurate mounting in the spectacle frame.

The chief feature of the invention consists in employing a mirror in making the protractor, that is, a plate of glass or other transparent material with the protractor lines and numerals thereof on the one surface and the other surface covered with reiiecting material to form amirror. In using this sort of protractor, it is adjusted With reference to the eyes of the inspector so that the protractor lines and numerals on the upper surface of the glass will coincide exactly With their reflection or images caused by the mirror so that the latter Will not be apparent along his line of vision.

In that position and condition of the pro-y tractor and inspector, his line of vision will.

be exactly and necessarily perpendicular with the reflector and the lens or blank thereon.

In using the ordinary protractor made .18 on the protractor.

of paperworwotheropaque .imaterialVor in usinga 'nakedfglass fprotractor, there is considerable diicullty inadjustingthesame With reference 5to thefeyes 4of =the inspector in order Ythat his-'lines of vision-Will bef-e5;h aetly. perpendicular to 4the pro-tractor :and thus 'enabler him 'to accurately `locate "the y lensthereon, particularly .if it be' a ibifocal,

lens. This present :invention vis tol'obvia'te this difficulty which isla condition yJknjoavn inthe fartsaslan Ierror'zdue :to "pnrallaxiz Therfull nature of the invention will be understood .from i the `accompany-ing v.drawings :and Ythe claims: -v v In the dra-Wings, Figure l-'is fap'erspective view of thel mirrored lprotractor, the reflected images of theprotract-orflines being indicated by dotted lines. Fig. 42 Iis a central cross-section lof a flat'mirrorejd fprotrac'tor. Y IFig. 8 -is similarsectionI of 'a concave convea7 Lmirroredprotractor. l

This protractoryis a' plate or diskflO[made o'f'glass or other transparentinaterial. :Upon

the one side thereof lines and numerals arel placed, the same as-in paper chart protractors heretofore used. The4 chart herein shown has a circle 11 concentric of the disk and two primary meridian lines l2 and 13V traversing the same. From the Vcircle radiating lines 14 areindicated representing various degrees of a circle and these de" grees are indicated by the numerals 15, so that each end of the meridian or line 12 is marked 180 and each end of the meridian line 13 is marked 90. On the meridian lines there are indicated millimeter scales as is Well known in the art and which need not be described particularly herein. There are also three curved lines 18 shown, being parts of circles of different curvatures tan- Iential With each other and located in the lower half of the circle 1l for the purposes of properly locating bifocal lenses or lens blanks on said protractor. The lens, not shown, so placed on they protractor With the division line between the bifocal surfaces thereof Will coincide with one of the lines Then the positions of tl e parts of the lens are indicated and located relative thereto as is Well known in theart. l

As shown in Fig. 2, theglass protractor plate is coated on the lower or other side following .descriptionuind A vision is'through the center, there will ber no vupper right hand.

by a coating 19 of reflecting material, such as 1s employed in making mirrors.l

In Fig. 3 there is shown a concave-convex protractor in the form of a segment or a hollow. l sphere whi'chfis amore. desirable form ormany vpurpos'es'tha'n the flatprotractor shown in Fig. 2. The curvature of the concavo-convex protractor is and should be preferably concentric with the eye of the observer while testing lenses, preferably with a radius of about` seven inches..

vWith the flat protractor4 mirror when the line of vision is through the center,.shadows of the other lines, atleast the outlying lines, will be observable. Fig. l shows said shadow lines as viewed Jfrom a point at the Vith the concavo-convex mirror protractor lwhen -the y, line of shadow lines visible, which makes it less i confusing and moresafe and accurate when in use. Y l

In using such :mirror protractor, the lens blank or lens is placed upon the protractor so as to register with the circle 11 and principal meridianlines; andfwh'en viewed from Ythe perpendicular, such lens will be correctly placed when no shadow lineis apparent in the line of vision. In theconcavofconvex lform when thus placed,no shadow linewill be apparent. It the shadow line is apparent in the line of vision, itis evidence that the Y lens is not correctly placed or marked. This makes an easily observable test,

developing center.

absolute accuracy in the vuse of the protractor. Y,

In order to conveniently support the lens) or lens blank to keep the lens `from injuring the markings 'on' the protractor,` three small buttons QI are secured-thereon properly equidistant from each other and from the So `far as this particular invention is concerned, it is immaterial how'the mirror is made or what sort of chart is indicatedL thereon, thenovel feature being a protractor made on or by use of a mirror.

The principle of this protractor is not limited to use in laying vout blanks and maring lenses, but is adapted for any use in'con# Y nection withY the optical business vWhere such protractorl is serviceable such as taking frame measurements with the lenses in the :trame and like uses.' y Y The invention claimed is: l l. A protractorfor optical purposes in cluding a transparentplatafan inwardly reliecting coating protractor markings on the vother surface thereof. c v. c Q. A. protractor for laying outl and.l inspecting lens blanks, lenses andthe like inon one surfacel thereof,v and cluding a transparent plate concavo-convex in form an inwardly reflecting coating on the convex surface thereof, and protractor markings on the concave surface'thereof.

In witness whereof, I have hereunto affixed my signature.

Lucian w. BUGBEE, JR. c. 

